AP Biology The Building Blocks 3.3 Nucleic Acids
Jan 08, 2016
AP Biology
The Building Blocks 3.3 Nucleic Acids
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HELIXHELIXHELIXHELIX
AP Biology 2006-2007
Nucleic AcidsInformation
storage
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Nucleic Acids Function:
store & transmit hereditary information
Examples: RNA (ribonucleic acid) DNA (deoxyribonucleic acid)
Structure: monomers = nucleotides
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Nucleotides 3 parts
nitrogen base (C-N ring) pentose sugar (5C)
ribose in RNA deoxyribose in DNA
phosphate (PO4) group
Are nucleic acidscharged molecules?
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RNA & DNA RNA
single nucleotide chain
DNA double nucleotide chain
N bases bond in pairs across chains
spiraled in a double helix double helix 1st proposed as structure of DNA
in 1953 by James Watson & Francis Crick (just celebrated 60th anniversary in 2013!)
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Types of nucleotides 2 types of nucleotides
different nitrogen bases purines
double ring N base adenine (A) guanine (G)
pyrimidines single ring N base cytosine (C) thymine (T) uracil (U)
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Building the polymer
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Nucleic polymer Backbone
sugar to PO4 bond phosphodiester bond
new base added to sugar of previous base
polymer grows in one direction N bases hang off the
sugar-phosphate backbone
Dangling bases?Why is this important?
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Pairing of nucleotides Nucleotides bond between
DNA strands H bonds purine :: pyrimidine A :: T
2 H bonds G :: C
3 H bonds
Matching bases?Why is this important?
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Information polymer Function
series of bases encodes information like the letters of a book
stored information is passed from parent to offspring need to copy accurately
stored information = genes genetic information
Passing on information?Why is this important?
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AA
A
A
TC
G
CG
TG
C
T
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DNA molecule Double helix
H bonds between bases join the 2 strands A :: T C :: G
H bonds?Why is this important?
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Copying DNA Replication
2 strands of DNA helix are complementary have one, can build other have one, can rebuild the
whole
Matching halves?Why is this
a good system?
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When does a cell copy DNA? When in the life of a cell does DNA have
to be copied? cell reproduction
mitosis gamete production
meiosis
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DNA replication“It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material.”
James WatsonFrancis Crick
1953
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Watson and Crick … and others…1953 | 1962
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Maurice Wilkins… and…1953 | 1962
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Rosalind Franklin (1920-1958)
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Interesting note… Ratio of A-T::G-C
affects stability of DNA molecule 2 H bonds vs. 3 H bonds biotech procedures
more G-C = need higher T° to separate strands
high T° organisms many G-C
parasites many A-T (don’t know why)
AP Biology 2006-2007
Macromolecule Review
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Carbohydrates Structure / monomer
monosaccharide
Function energy raw materials energy storage structural compounds
Examples glucose, starch, cellulose, glycogen
glycosidic bond
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Lipids Structure / building block
glycerol, fatty acid, cholesterol, H-C chains
Function energy storage membranes hormones
Examples fat, phospholipids, steroids
ester bond (in a fat)
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Proteins Structure / monomer
amino acids levels of structure
Function enzymes defense transport structure signals receptors
Examples digestive enzymes, membrane
channels, insulin hormone, actin
peptide bond
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Nucleic acids Structure / monomer
nucleotide
Function information storage
& transfer
Examples DNA, RNA
phosphodiester bond